U.S. Pat. No. 4,296,889 discloses a method of breaking the formation of ribbons while winding textile yarns into a cross-wound package by a system known as "wobbling" in which the traversing frequency of the yarn guide is temporarily varied by accelerating and decelerating the traverse motion of the yarn guide. This system has the disadvantage that the takeup speed, which is the geometrical sum of the circumferential speed of the package and the yarn traversing speed, is varied and this results in undesirable changes in yarn tension.
It is also known from U.S. Pat. No. 3,730,448 to periodically shorten the stroke (stroke modification) when producing a cross-wound yarn package. In accordance with the method of this patent, an additional speed is positively or negatively superimposed on the traverse motion drive, i.e., a grooved roll, which always traverses the same stroke length. As a result, the traversing yarn guide crosses the stroke length assigned to it at the same traversing frequency, but at a changed traversing speed, if the traversing stroke is modified. Likewise, the method of the periodic stroke modification serves to build up an exactly cylindrical or biconical package with straight or inclined opposite sides. Also, in accordance with this method, a variation of the traversing speed causes a change of the winding speed, resulting in an undesirable change of the yarn tension.
To avoid such unacceptable changes in the yarn tension, U.S. Pat. No. 4,325,517 suggests a method in which the ribbon breaking and the stroke modification should simultaneously occur. As a result, the variation of the traversing speed for the purpose of ribbon breaking is largely compensated by the variation of the traversing speed for the purpose of stroke modification. This latter method is further developed in a manner disclosed in U.S. Pat. No. 4,659,027 so that uniformly cylindrical packages can be built up in order to permit the yarn to be unwound at speeds higher than 1,000 m/min without any problems.